Dell Monitor in Sleep Mode

I have a flat screen monitor manufactured in May 2002. The UPC code is DS/N CN-03k648-466333-25U-10X2.

It can take a long time (up to an hour) to "wake up" after the machine is booted. I have 2 computers (both Dell). The monitor does the same thing with both computers. The other monitor that works well works well with both computers, so I'm almost positive that any changes I made in the control panel are not affecting it.